Most of backlight modules are constituted by a light source, a light guide plate, a reflector sheet and an optical film unit which are assembled together through a fixed frame.
However, with the development of the display technology, it is possible to develop multi-screen and multi-surface display (e.g., a main interface of a mobile phone and a side edge of the mobile phone are all used for display) to increase display area. It can be seen that, in case where a main screen and a side surface of the mobile phone are both required to perform display, the existing backlight modules can only provide backlight to the main screen and cannot satisfy demands of multi-screen and multi-surface display.